1. Field of the Invention
The present invention pertains to the field of materials used in various locations throughout vehicles for insulating and dampening sound from being carried into the passenger compartment. The most common area where such material is used is behind the dashboard in order to minimize the transmission of sound from the engine compartment into the passenger compartment.
Due to the convoluted formation of this "fire wall area" it is necessary that the sound insulating material be non-linear in such a manner as to be formed as close as possible to the exact configuration of the area to be insulated.
2. Description of the Prior Art
The preferred method used heretofore for forming such acoustical insulation has been vacuum forming. Other methods would include curtain coating, roller coating, spraying, and slush molding. However, the present invention utilizes a molded elastomer configuration which can provide an overall structure which is more tailored to the specific application. That is, by molding the insulation layer of the filled polyurethane elastomer, a moderately rigid configuration of the overall insulating member can be achieved. Then, with the application of the polyurethane foam layer to the surface of this insulation layer, and with the ability made possible by the molded configuration, and in this case by the use of a foaming fixture or foaming mold, it is possible to provide variations in the thickness of the insulating material in proportion to the acoustical activity in the immediate neighborhood thereadjacent. This type of efficiency in production of insulating material has not been available heretofore due to the usage of vacuum forming other methods rather than molding as in the present invention.